Scleral Versus Corneal RGP Contact Lenses in Irregular Cornea Disorders

NCT02444923 | Completed DMC

• 1 other identifier: Levita
• Study Type: interventional
• Target: 30
• Locations: 1 country
• Sites: 1

Brief Summary

The most common causes for irregular cornea (IC) in hospital contact lens practice are Keratoconus (KC) and related cornea thinning disorders. These conditions cause mild to marked impairment of vision and cannot be effectively corrected by spectacles and soft contact lenses. The gold standard in the management of KC is Corneal Rigid Gas Permeable contact lenses (corneal lenses), which correct approximately 90% of the corneal irregularity. Compared with a normal cornea, the cornea in KC is irregular and this results in a compromise to the fit of rigid corneal lenses. Specifically, they bear on the cornea and this, together with the vulnerability of the cornea in KC, are implicated in corneal scarring, and disease progression as well as a significantly reduced vision related quality of life (QoL) in KC compared with corneal lens wearers who have no KC. In cases where the compromise fit of corneal lenses proves problematic, large diameter Scleral RGP contact lenses (scleral lenses) may be used as a problem solver. Unlike the smaller corneal lenses which bear on the cornea, the scleral lenses completely bridge over the cornea and bear on the sclera. The aim of this research is to investigate the performance of scleral lenses in KC participants who habitually wear corneal lenses. The research question: is there a measurable difference in the visual performance and visual quality of life in participants with Irregular cornea disorders like keratoconus and other related conditions, who habitually wear corneal lenses in comparison with scleral lenses.

Conditions

Irregular; Contour of Cornea; Keratoconus; Pellucid Marginal Corneal Degeneration; Injury of Cornea; Irregular Astigmatism

Keywords

Corneal rigid gas permeable contact lenses; Scleral rigid gas permeable contact lenses; Custom Scleral contact lenses; Keratoconus; Irregular cornea; Pellucid marginal degeneration; Post keratoplasty irregular cornea; Post refractive surgery irregular cornea; Traumatic irregular cornea

Outcome Measures

Primary Outcomes (1)

• Monocular Best Corrected Visual Acuity (BCVA)

  High contrast BCVA will be measured by the specially constructed crowded, Logarithmic Minimum Angle of Resolution (LogMAR), Early Treatment Diabetic Retinopathy Survey (ETDRS) letter charts. An average score of 3 different, randomly presented charts will be taken as the final acuity score. It will be performed utilising the CSV1000E, under the established recommended standardised testing conditions utilised in a multitude of research protocols.

  Baseline and after a minimum of 6 weeks of wear of each contact lens type, report at study completion

Secondary Outcomes (4)

• Contrast Sensitivity Function

  Measure at recruitment (Baseline), subsequent measurement after 6 weeks of wear, of lens 1 and 6 weeks of wear of lens 2. Study completion after 6-12 months.

• The National Eye Institute-Visual Function Questionnaire (NEI-VFQ)

  Measure at recruitment (Baseline), subsequent measurement after 6 weeks of wear, of lens 1 and 6 weeks of wear of lens 2. Study completion after 6-12 months.

• The Levit Subjective Comfort and Vision Scales

  Measure at recruitment (Baseline), subsequent measurement after 6 weeks of wear, of lens 1 and 6 weeks of wear of lens 2. Study completion after 6-12 months.

• The final lens choice

  At study completion after 6-12 months

Study Arms (2)

Scleral rigid gas permeable contact lenses

EXPERIMENTAL

The experimental intervention is the Scleral Rigid Gas Permeable contact lens (SRGPcl), Zenlens™. These lenses are designed to bridge the cornea and fit in alignment with the sclera, thus avoiding any detrimental effects associated with corneal contact.

Device: Scleral rigid gas permeable contact lenses (SRGPcl) (Zenlens™); Device: Corneal Rigid gas Permeable contact lenses (CRGPcl) (Rose K2)

Corneal rigid gas permeable contact lenses

PLACEBO COMPARATOR

The control intervention is the RoseK2™ Corneal Rigid Gas Permeable contact lens (CRGPcl). Corneal lenses are considered the gold standard in the management of the visual disability due to keratoconus and other related irregular cornea disorders.

Device: Scleral rigid gas permeable contact lenses (SRGPcl) (Zenlens™); Device: Corneal Rigid gas Permeable contact lenses (CRGPcl) (Rose K2)

Interventions

Scleral rigid gas permeable contact lenses (SRGPcl) (Zenlens™) DEVICE

Custom manufactured scleral rigid gas permeable contact lenses. These lenses are designed to fit the eye with high level of precision. The aim is to bridge the cornea and fit in alignment with the sclera, thus avoiding any detrimental effects associated with the corneal rigid gas permeable lenses.

Also known as: Scleral lenses, Zenlens, Custom Scleral Contact Lenses, RGP Scleral Lenses

Corneal rigid gas permeable contact lenses; Scleral rigid gas permeable contact lenses

Corneal Rigid gas Permeable contact lenses (CRGPcl) (Rose K2) DEVICE

The Rose K2 lens is a widely used corneal gas permeable lens designed for keratoconus and other irregular cornea disorders

Also known as: Rose K2 corneal gas permeable contact lenses

Corneal rigid gas permeable contact lenses; Scleral rigid gas permeable contact lenses

Eligibility Criteria

• Age: 18 Years - 69 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• Diagnosis of keratoconus or related corneal irregularity
• Age 18 years to 69 years.

You may not qualify if:

• Good visual quality with soft contact lenses and or spectacles

Sponsors & Collaborators

• London South Bank University: lead

Study Sites (1)

Central Middlesex Hospital

London, NW10 7NS, United Kingdom

Location

Related Publications (1)

• Visser ES, Van der Linden BJ, Otten HM, Van der Lelij A, Visser R. Medical applications and outcomes of bitangential scleral lenses. Optom Vis Sci. 2013 Oct;90(10):1078-85. doi: 10.1097/OPX.0000000000000018.

  PMID: 23974663 RESULT

Related Links

• Institute of Optometry

MeSH Terms

Conditions

Keratoconus; Corneal Injuries

Condition Hierarchy (Ancestors)

Corneal Diseases; Eye Diseases; Eye Injuries; Facial Injuries; Craniocerebral Trauma; Trauma, Nervous System; Nervous System Diseases; Wounds and Injuries

Study Officials

• Alexander Levit, FCOptom

  London South Bank Unversity

  PRINCIPAL INVESTIGATOR

• Martin Benwell, PhD

  London South Bank University

  STUDY DIRECTOR

• Bruce Evans, PhD

  Institute of Optometry

  STUDY CHAIR

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: SINGLE
• Who Masked: INVESTIGATOR
• Masking Details: The practitioner who measures the visual outcomes is naive to the type of lens the participant is wearing
• Purpose: TREATMENT
• Intervention Model: CROSSOVER
• Sponsor Type: OTHER
• Responsible Party: SPONSOR

Model Details: Randomised control trial with a 2x2 crossover

Study Record Dates

• First Submitted: April 21, 2015
• First Posted: May 15, 2015
• Study Start: October 25, 2015
• Primary Completion: January 29, 2019
• Study Completion: January 29, 2019
• Last Updated: August 19, 2019

Record last verified: 2019-08

Data Sharing

• IPD Sharing: Will not share

Locations

GB (1)